President John Kennedy pins NASA's Distinguished Service Medal on Shepard's chest, May 8, 1961. Two weeks later, JFK famously declared: "I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the Earth."
"I was the pool photographer on the pad that night for the whole world," photographer Ralph Morse told LIFE. "Everything is fine until some NASA idiot comes over and says, 'No photographer is allowed to use two cameras.' What? I have no time to argue, the van is arriving with Alan, so I look around for a familiar face, and there's [astronaut Scott] Carpenter. I ask him to stand by the tripod and fire off some frames with the cable trigger when Alan comes out. I got my picture of Alan -- but Scott's the one who actually tripped the shutter on this one."
Six of the seven original Mercury astronauts in early 1961, shortly after three of them -- Shepard, John Glenn, and Gus Grissom -- were named candidates for the May 1961 space flight. (That's Shepard, clowning, with Gordon Cooper, Donald "Deke" Slayton, Glenn, Scott Carpenter, and Walter Schirra. Grissom was away, on missile-tracking duty.) "After I made this picture," Morse recently told LIFE.com, "I said to Shepard, 'Alan, you should never do that sort of stuff. That's the shot the magazine will run!' And I was right. A few weeks later, out of all the pictures I took during that press conference, this is the photograph that appeared in LIFE."
Unpublished until now, a party for astronauts and other Project Mercury personnel, Florida, May 1961. While his 1961 flight proved a huge boost for NASA, Shepard did not, in fact, orbit the Earth. His was a "sub-orbital" trajectory, meaning he and his Freedom 7 craft reached a maximum altitude of around 115 miles -- but did not come close to a true orbit or circling of the globe.
Unpublished until now, the Redstone rocket on which Alan Shepard flew into space, May 5, 1961 | "I never have been my own favorite subject," Shepard once told LIFE, when asked how he felt about the rewards and dangers inherent in Project Mercury. "And I don't think I've found anything new about myself since I've been in this program. We were asked to volunteer, not to become heroes. As far as I'm concerned, doing this is just a function of maturity. If you don't use your experience, your past is wasted, and you are betraying yourself."
Unpublished until now, John Glenn at Mission Control prior to Alan Shepard's May 1961 flight. "One thing that constantly impressed me," Ralph Morse told LIFE.com, "was how utterly capable these Mercury guys were in so many different areas. It was kind of unbelievable. And they had their own language, this very technical lingo they'd developed after spending so much time together. That's why, when someone had to talk to an astronaut during a flight, it helped if it was another astronaut."
Among the most consistently quotable of all NASA's astronauts, Shepard reportedly joked to technicians who rode with him to the launch pad: "You should have courage and the right blood pressure" if you want to succeed as an astronaut. "And four legs ... You know, they really wanted to send a dog, but they decided that would be too cruel." Above: Shepard makes his way to the launch pad, with Gus Grissom close behind. In Shepard's right hand: a portable air conditioner to cool the inside of his pressure suit before he enters the capsule.
"Very early on, I wanted a picture of the seven guys in their space suits. NASA said no. They wouldn't allow it," Morse told Life. "Besides, they said, all the astronauts would never wear the suits at the same time. Now, each of these suits cost a hundred grand -- big money back then -- and, you know, ladies want to see what a hundred thousand dollar dress looks like. But the answer from NASA was always, No, no, no.
"Finally, one afternoon, Shorty Powers -- a public affairs guy for NASA and, as far as I could tell, a frustrated astronaut -- Shorty says to me, 'Ralph, you know that picture you want to take? We decided to let you do it. Tonight. But you gotta get the guys together -- and you gotta get the suits on them.'" Above: Mercury astronauts don space suits, 1959, Virgina.
For more exclusive photos and the stories behind the images, see the full gallery at Life.com.
On May 5, 1961, 37-year-old Alan Shepard blasted off from Cape Canaveral on a historic flight that marked the moment the U.S. caught up to Russia in the Space Race. Here, rare and never-seen photographs from LIFE of that amazing era.For far more photos, see the full gallery at Life.com.